User's Manual

48-41
Firstly enable IGMP snooping in the VLAN it is located (Here it is assumed to be in VLAN2)
EC(config)#ip igmp snooping
EC(config)#ip igmp snooping vlan 2
After that, configure relative destination control access-list, and configure specified IP address to use that
access-list.
Switch(config)#access-list 6000 deny ip any 238.0.0.0 0.255.255.255
Switch(config)#access-list 6000 permit ip any any
Switch(config)#multicast destination-control
Switch(config)#ip multicast destination-control 10.0.0.0/8 access-group 6000
In this way, users of this network segment can only join groups other than 238.0.0.0/8.
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Multicast strategy
Server 210.1.1.1 is distributing important multicast data on group 239.1.2.3, we can configure on its join-in
switch as follows:
Switch(config)#ip multicast policy 210.1.1.1/32 239.1.2.3/32 cos 4
In this way, the multicast stream will have a priority of value 4 (Usually this is pretty higher, the higher possible
one is protocol data; if higher priority is set, when there is too many multicast data, it might cause abnormal
behavior of the switch protocol) when it gets to other switches through this switch.
48.8.4 DCSCM Troubleshooting
The effect of DCSCM module itself is similar to ACL, and the problems occurred are usually related to
improper configuration. Please read the descriptions above carefully. If you still can not determine the cause
of the problem, please send your configurations and the effects you expect to the after-sale service staff of our
company.
48.9 IGMP
48.9.1 Introduction to IGMP
IGMP (Internet Group Management Protocol) is the protocol in TCP/IP protocol family which is responsible for
IP multicast member management. It is used to set up and maintain multicast group member relationship
between IP host and its neighbor multicast switches. IGMP does not include the spread and maintenance of
relation information of group members among multicast switches, this work is accomplished by each multicast
routing protocol. All hosts participating in multicast must implement IGMP protocol.